setstate object:{array:[]} in reactjs how could i add the **key and value inside the array which is in the state object**?

Question

key and value inside the array which is in the state object

this.state = { frequency: { days: [], startdate: "", customdate: "" }, };

how could i add the key ad value inside the days array?

Answer 1

You can modify your state by using setState like this:

this.setState({frequency: {...this.state.frequency, days: [...this.state.frequency.days, day]}});

Answer 2

function addKeyValue(key, value) {

  this.setState(state => ({
    ...state,
    frequency: {
       ...state.frequency,
       days: [...state.frequency.days, {[key]: value}]
    }
  })
}

--Edit

Removing the key is a bit trickier.

function removeKeyValue(key, value) {

  this.setState(state => {
    const days = state.frequency.days;
    const dayIndex = days.findIndex(pr => pr[key] === value);
    const day = {...days[dayIndex]};
    delete day[key];

    return {
      ...state,
      frequency: {
         ...state.frequency,
         days: [...days.slice(0, dayIndex),
            day,
            ...days.slice(dayIndex + 1)]
      }
    }
  }
}